CVE-2025-40839.1CriticalCWE-653

CVE-2025-4083: Process isolation bypass using "javascript:" URI links in cross-origin frames

Mozilla · Firefox

Vendor fix available · Affected: Mozilla Firefox · Exploitation: unlikely (under 1%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

0.5%probability of exploitation in the next 30 days

40th percentile

050100

Higher than 40% of scored CVEs

9.1CriticalCVSS 3.1

LowMediumHighCrit.

DescriptionCVE.org

A process isolation vulnerability in Thunderbird stemmed from improper handling of javascript: URIs, which could allow content to execute in the top-level document's process instead of the intended frame, potentially enabling a sandbox escape. This vulnerability was fixed in Firefox 138, Firefox ESR 128.10, Firefox ESR 115.23, Thunderbird 138, and Thunderbird 128.10.

Affected products2

From the CVE record. A product or version that is not listed is unknown, not unaffected.

Mozilla · FirefoxVersions not stated
Mozilla · ThunderbirdVersions not stated

On the Atlas

Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.

Open the Atlas

Exploitation: Unlikely (under 1%). EPSS under 1%, or no score yet.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Improper Isolation or Compartmentalization · Access Control
Vendor: Mozilla
Published: April 2025
Band: Unlikely (under 1%), April 2025

CoverageNo articles yet

No CyberSIXT article names CVE-2025-4083 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.